The effects of halothane or isoflurane, alone and in combination with propofol or thiopental were investigated for their effects on intracranial pressure (ICP) in the rabbit, with inducing artificially-increased ICP with an intracranial balloon. The higher the end-tidal concentrations of either halothane or isoflurane, the lower the mean arterial pressures (MAP) and cerebral perfusion pressures (CPP). However, the ICP was not influenced by the depth of anesthesia for either inhalation anesthetics. The mean ICPs at 1.5 MAC of halothane and isoflurane were 14 +/- 2 and 20 +/- 2 mmHg, respectively. With the increase of intracranial volume using a 0.7 ml-saline balloon, the ICPs were increased to 193 and 205% in halothane and isoflurane anesthesia, respectively. The ICPs were returned to the levels prior to balloon inflation by the injection of thiopental or propofol. The authors conclude that propofol could be used to reduce ICP under halothane or isoflurane anesthesia if it is ascertained to have the characteristics of a balanced coupling between cerebral metabolism and blood flow like barbiturates do and that either halothane or isoflurane with increased concentrations may decrease MAP without significant change of ICP.
*Anesthesia ; Animal ; Female ; *Halothane ; Intracranial Pressure/*drug effects ; *Isoflurane ; Male ; Propofol/*pharmacology ; Rabbits ; Thiopental/*pharmacology

OBJECTIVETo observe the effects of isoflurane combined with diltiazem on human sperm motility in vitro and to investigate its possible mechanism.

METHODSTen normal semen samples were collected, each divided into 9 groups, one as the control and the others treated in vitro with different concentrations of diltiazem or diltiazem +4.2% isoflurane for 1 hour. Sperm motility was observed with the computer-assisted sperm analyzer.

RESULTSCompared with the control, diltiazem significantly decreased sperm motility at the concentrations of 0.01 g/L, 0.04 g/L, 0.2 g/L and 1 g/L in a dose-dependent manner, and reduced it to approximately 0% at 1 g/L. When combined with 4.2% isoflurane, diltiazem obviously increased sperm motility at 0.01 g/L, markedly decreased it at 0.2 g/L, and effected no significant difference at 0.04 g/L and 1 g/L as compared with the corresponding concentrations of diltiazem alone.

CONCLUSIONThe stimulating effect of isoflurane on sperm motility may be associated with the calcium ion channel in sperm. When completely blocked by diltiazem, this effect may turn into an inhibition of sperm motility.

Adult ; Calcium Channel Blockers ; pharmacology ; Diltiazem ; pharmacology ; Drug Antagonism ; Humans ; Isoflurane ; pharmacology ; Male ; Sperm Motility ; drug effects

OBJECTIVETo study the effects of inhaled anesthetics on human sperm motility in vitro.

METHODSSperm samples were obtained from 20 healthy men by masturbation and prepared by the swim-up technique. The effects of isoflurane and sevoflurane at the clinical concentration (1.4%-5.6%) and high concentration (5.6%-84%) on human sperm motility in vitro were observed at 25 degrees C by the computer-assisted sperm analysis (CASA).

RESULTSThe sperm vitality and motility were significantly increased on 0.5-4 h exposure to isoflurane at the clinical concentration and decreased gradually at high concentration (42%-84%). The effect of isoflurane on human sperm motility and vitality at the clinical concentration was reversible when the anesthetic withdrawn. Sevoflurane had no effects on human sperm motility and vitality at either the clinical or high concentration.

CONCLUSIONIsoflurane has a reversible increasing effect at the clinical concentration and a significant decreasing effect at the high concentration on the motility and vitality of human sperm, while sevoflurane does not affect human sperm motility and vitality at either concentration.

Adult ; Anesthetics, Inhalation ; pharmacology ; Humans ; Isoflurane ; pharmacology ; Male ; Methyl Ethers ; pharmacology ; Sperm Motility ; drug effects ; Spermatozoa ; cytology ; drug effects ; physiology

Anesthetics, Inhalation ; pharmacology ; Child ; Electrocardiography ; Heart Rate ; drug effects ; Humans ; Isoflurane ; analogs & derivatives ; pharmacology ; Methyl Ethers ; pharmacology

BACKGROUND: The actions of mivacurium (MVC), a new benzylisoquinolinium nondepolarizing neuromuscular blockade, may be potentiated if preceded by succinylcholine (SCh). Additionally, the interaction between inhalational anesthetics and MVC has not yet been established in the cat. The effect of enflurane or isoflurane on the neuromuscular blocking action of MVC by preadministrated succinylcholine was evaluated. METHOD: Twelve cats, either sex, were assigned into two groups, based on the preadministration of succinylcholine (SCh) what about the sciatic nerve-anterior tibialis preparation, cumulative dose-response study and the estimation of recovery profiles from the twitch depression of about 95 % under pentobarbital, isoflurane or enflurane anesthesia was done. The ED50, ED95 and the recovery profiles were compared. RESULTS: The ED50 and ED95 under isoflurane (24.5 & 37.3) and enflurane (20.6 & 32.1) were significantly lower than those under pentobarbital anesthesia(28.4 & 42.9 ug/kg, respectively) without preadministrated SCh. The effective doses of MVC with preadministrated SCh had the same manner. The recovery profiles under enflurane anesthesia were significantly slower than those under pentobarbital anesthesia. The higher the recovered twitch height under enflurane anesthesia, the slower the recovery speed. CONCLUSION: The potency of MVC and recovery profiles under inhalation anesthetics are greater than those under pentobarbital. However, preadministrated SCh causes no significant difference in its potency or recovery.
Anesthesia ; Anesthetics ; Anesthetics, Inhalation ; Animals ; Cats* ; Depression ; Enflurane* ; Isoflurane* ; Neuromuscular Blockade* ; Pentobarbital ; Pharmacology ; Succinylcholine*

BACKGROUNDThe mechanisms of action for volatile anesthetics remain unknown for centuries partly owing to the insufficient or ineffective research models. We designed this study to develop three strains derived from a wild-type Drosophila melanogaster with different sensitivities to volatile anesthetics, which may ultimately facilitate molecular and genetic studies of the mechanism involved.

METHODSMedian effective doses (ED(50)) of sevoflurane in seven-day-old virgin female and male wild-type Drosophila melanogaster were determined. The sensitive males and females of percentile 6 - 10 were cultured for breeding sensitive offspring (S(1)). So did median ones of percentile 48 - 52 for breeding median offspring (M(1)), resistant ones of percentile 91 - 95 for breeding resistant offspring (R(1)). Process was repeated through 31 generations, in the 37th generation, S(37), M(37) and R(37) were used to determine ED(50) for enflurane, isoflurane, sevoflurane, desflurane, halothane, methoxyflurane, chloroform and trichloroethylene, then ED(50) values were correlated with minimum alveolar concentration (MAC) values in human.

RESULTSFrom a wild-type Drosophila melanogaster we were able to breed three strains with high, median and low sevoflurane requirements. The ratio of sevoflurane requirements of three strains were 1.20:1.00:0.53 for females and 1.22:1.00:0.72 for males. Strains sensitive, median and resistant to sevoflurane were also sensitive, median and resistant to other volatile anesthetics. For eight anesthetics, ED(50) values in three strains correlated directly with MAC values in human.

CONCLUSIONSThree Drosophila melanogaster strains with high, median and low sensitivity to volatile anesthetics, but with same hereditary background were developed. The ED(50) are directly correlated with MAC in human for eight volatile anesthetics.

Anesthetics, Inhalation ; pharmacology ; Animals ; Chloroform ; pharmacology ; Drosophila melanogaster ; drug effects ; growth & development ; Enflurane ; pharmacology ; Female ; Halothane ; pharmacology ; Isoflurane ; analogs & derivatives ; pharmacology ; Male ; Methoxyflurane ; pharmacology ; Methyl Ethers ; pharmacology ; Trichloroethylene ; pharmacology

OBJECTIVETo investigate the effect of different fresh gas flow (FGF) rates on isoflurane pharmacokinetics during anesthesia induction.

METHODSSixty female patients (ASA class I-II, age range of 18-49 years) scheduled for gynecological laparoscopic surgery were randomly divided into groups I, II, and III (n=20) for isoflurane inhalation with FGF rate of 1, 2, and 3 L/min, respectively. Each group was further divided into two equal subgroups according to the setting concentration of the isoflurane vaporizer at 1% (groups I 1, II 1, and III 1) and 2% (groups I 2, II 2, and III 2). Isoflurane with different setting concentrations was administered under different FGFs in the patients after tracheal intubation following anesthesia induction, and the inspiratory concentration (CIiso) and expiratory concentration (CEiso) of isoflurane in the airway were monitored and recorded every 3 min for totalling 18 min, with the observation time points marked as T1 to T6, respectively.

RESULTSCIiso and CEiso varied significantly at different time points and between different subgroups (P<0.05). In each subgroup, CIiso and CEiso increased along with time and reached a relatively stable stage at 9 min, but failed to reach the setting concentration during the observation period. At different observation time points, CIiso and CEiso in the subgroups with setting isoflurane concentration of 2% were almost twice as much as that in the subgroups with setting isoflurane concentration of 1%.

CONCLUSIONSCIiso and CEiso increase along with time lapse in all the groups and reach a relatively stable stage at 9 min after inhalation initiation, but can not reach the setting concentration. The larger the FGF and setting concentration, the faster CIiso and CEiso increase.

Adolescent ; Adult ; Anesthesia ; methods ; Female ; Gases ; pharmacology ; Humans ; Isoflurane ; pharmacokinetics ; Middle Aged ; Respiration ; Time Factors ; Young Adult

Animals ; Cardiopulmonary Bypass ; Dogs ; Female ; Isoflurane ; pharmacology ; Lung ; blood supply ; Male ; Random Allocation ; Reperfusion Injury ; prevention & control

In this study, we tested the hypothesis that volatile anesthetic enhancement of muscle relaxation is the result of combined drug effects on the nicotinic acetylcholine receptors. The poly A m RNA from muscle by isolation were microinjected into Xenopus oocytes for receptor expression. Concentration-effect curves for the inhibition of Ach-induced currents were established for vecuronium, rocuranium, and isoflurane. Subsequently, inhibitory effects of NDMRs were studied in the presence of the isoflurane at a concentration equivalent to half the concentration producing a 50% inhibition alone. All tested drugs produced rapid and readily reversible concentration-dependent inhibition. The 50% inhibitory concentration values were 889 micromol/L (95% CI: 711-1214 micromol). 33.4 micromol (95% CI: 27.1-41.7 nmol) and 9.2 nmol (95% CI: 7.9-12.3 nmol) for isoflurane. rocuranium and vecuronium, respectively. Coapplication of isoflurane significantly enhanced the inhibitory effects of rocuranium and vecuronium, and it was especially so at low concentration of NMDRs. Isoflurane increases the potency of NDMRs, possibly by enhancing antagonist affinity at the receptor site.
Androstanols ; pharmacology ; Anesthetics, Inhalation ; pharmacology ; Animals ; Drug Synergism ; Female ; Isoflurane ; pharmacology ; Neuromuscular Blocking Agents ; pharmacology ; Neuromuscular Junction ; drug effects ; Neuromuscular Nondepolarizing Agents ; pharmacology ; Oocytes ; Receptors, Nicotinic ; drug effects ; Vecuronium Bromide ; pharmacology ; Xenopus laevis

In this study, we tested the hypothesis that volatile anesthetic enhancement of muscle relaxation is the result of combined drug effects on the nicotinic acetylcholine receptors. The poly A m RNA from muscle by isolation were microinjected into Xenopus oocytes for receptor expression. Concentration-effect curves for the inhibition of Ach-induced currents were established for vecuronium, rocuranium, and isoflurane. Subsequently, inhibitory effects of NDMRs were studied in the presence of the isoflurane at a concentration equivalent to half the concentration producing a 50% inhibition alone. All tested drugs produced rapid and readily reversible concentration-dependent inhibition. The 50% inhibitory concentration values were 889 micromol/L (95% CI: 711-1214 micromol). 33.4 micromol (95% CI: 27.1-41.7 nmol) and 9.2 nmol (95% CI: 7.9-12.3 nmol) for isoflurane. rocuranium and vecuronium, respectively. Coapplication of isoflurane significantly enhanced the inhibitory effects of rocuranium and vecuronium, and it was especially so at low concentration of NMDRs. Isoflurane increases the potency of NDMRs, possibly by enhancing antagonist affinity at the receptor site.
Androstanols/*pharmacology ; Anesthetics, Inhalation/pharmacology ; Drug Synergism ; Isoflurane/*pharmacology ; Neuromuscular Blocking Agents/*pharmacology ; Neuromuscular Junction/drug effects ; Neuromuscular Nondepolarizing Agents/*pharmacology ; Oocytes ; Receptors, Nicotinic/*drug effects ; Vecuronium Bromide/pharmacology ; Xenopus laevis